This appears to be the EMD GP-40X forerunner to the GP-50. There were 4 sets of these delivered to 4 customers, a total of 20 locomotives I believe. Buyers were Santa Fe, Southern, UP, and SP. The Santa Fe and Southern versions are shown here. The UP and SP engines were similar, except that they had HT-B trucks, 2 axle versions of the HT-C trucks that went into production on the Dash-2 locomotives. The HT-B trucks never went into production. The SP locos also had the typical SP light package.
An interesting choice for Athearn to make for a new locomotive, and personally frustrating since I spent some time not all that long ago scrounging around to locate one of the Overland brass models (UP in my case).
